Conventionally, in order to process a biological substance such as DNA, solutions such as; a magnetic particle suspension for use in the processing, a specimen solution, a reagent solution required for the processing of the specimen, a washing liquid, and the like are dispensed from a group of reagent etc. containers previously storing these solutions, and arrayed in accordance with the order of processing, in two or more liquid storage units for use in the processing, using a dispenser device. After the solutions have been arrayed, the magnetic particle suspension is sucked from and discharged into the first liquid storage unit using at least one processing nozzle which has at least one distal end insertable into the respective liquid storage units, for sucking and discharging a liquid through the distal end. By so doing, the magnetic particles such as magnetized silica and the target DNA contained in the specimen are captured, and a magnetic field is applied to the interior of the processing nozzle to thereby attract the magnetic particles to the inner wall of the distal end of the processing nozzle to effect separation of the magnetic particles. The residual liquid after the attraction of the magnetic particles is discharged into the first liquid storage unit, and then the magnetic particles are moved to the second liquid storage unit while being attracted to the inner wall of the distal end. After the movement, the distal end of the processing nozzle is inserted into the second liquid storage unit, and the solution stored in the storage unit is sucked and discharged in a state where the magnetic field has been cancelled, to thereby re-suspend the magnetic particles in the liquid. Through repetitive sucking and discharging, the magnetic particles are washed. After the washing operation, the liquid is sucked and a magnetic field is applied to the distal end to attract the magnetic particles to the inner wall thereof. Then, the residual liquid is discharged into the second liquid storage unit. Next, the washed magnetic particles are moved to the third liquid storage unit while being attracted to the inner wall. After the movement, the distal end of the processing nozzle is inserted into the third liquid storage unit, and the dissociation solution stored in the storage unit is sucked and discharged, to thereby dissociate the DNA captured on the magnetic particles from the magnetic particles. By so doing, a DNA solution can be obtained (Patent Documents 1 and 2).
As described above, in the conventional processing of a biological substance using magnetic particles, first, liquid storage units of a number equal to the number of steps of the processing are prepared, and liquids such as a solution required for processing are dispensed and arrayed by the respective steps. After the solutions have been arrayed, the liquid contained in each liquid storage unit is respectively sucked with or without repetitive sucking and discharging using the processing nozzle. Then, a magnetic field is applied to thereby attract the magnetic particles to the inner wall of the distal end to effect separation of the magnetic particles. The residual liquid is discharged into each liquid storage unit, and then the processing nozzle is moved to the next liquid storage unit while the magnetic particles are being attracted to the inner wall, followed by repetition of similar processing operations for a number of times of the processing steps.
In this manner, in the conventional processing, two or more containers corresponding to the number of the processing steps need to be prepared, in addition to the containers previously storing the reagent or other substances, and the reagent or other substances need to be dispensed and arrayed therein in advance. In particular, in the case of simultaneous processing of a large number of specimens such as specimens extracted from 96 subjects, for example, arrays of the number of steps each having 96 wells in a matrix form (8 rows×12 columns) need to be additionally prepared and arranged. For this reason, there has been a problem in that a large working space may be required, and the working efficiency in terms of space may be lowered.
Moreover, in the conventional processing, after the reagent or other substances required for processing have been dispensed into the respective liquid storage units of a number equal to the number of steps, the nozzle of the dispenser device is fitted with a distal end for processing, to start execution of the processing. Furthermore, since the processing of each liquid storage unit is shifted to the next liquid storage unit while the liquid used in each liquid storage unit is discharged into the liquid storage unit, it takes time until the completion of the processing due to; the time for dispensing the reagent or other substances into each liquid storage unit, the time for sucking the reagent or other substances and attracting the magnet particles, and the time for discharging the residual liquid taken at each step. Therefore, there has been a problem in that a lengthy working time may be required, and the working efficiency in terms of time may be impaired.
In response to this, the inventor of this application has invented a vessel with an inside bottom formed in an appropriate shape so that the whole amount of a liquid contained in the vessel can be reliably sucked using the distal end of a dispensing nozzle (Patent Document 3), and has shown that the use of this invention enables reliable processing of a predetermined amount of liquid without processing an excessive liquid amount exceeding a specified liquid amount for compensating for residual liquid loss in each liquid storage unit. This has led to a finding of the inventor in which the use of this invention enables improvement in the working efficiency of processing using magnetic particles.
[Patent Document 1] Japanese Unexamined Patent Publication No. Hei 8-62224
[Patent Document 2] Japanese Unexamined Patent Publication No. Hei 8-320274
[Patent Document 3] International Patent Publication No. WO 1997/005492